FADEC Malfunctions?

[SHortshaft]

The Indian operator of a Bell 407 has indicated that they believe the loss of power and rotor rpm experienced during a recent training flight, and which resulted in a heavy landing complete with tail boom separation, was as a result of a FADEC malfunction.

Have there been many other alleged or suspected FADEC malfunctions on the Bell 407 that have been kept as quiet as this one? Does anyone know of any others in the last few years?

[407 too]

"that they believe" --- i don't get it :confused:

if they had a FADEC failure, degrade or fault, they would have had, at least, caution lights on the panel - (if working as advertised)

[McGowan]

407 too is right, if there was any kind of FADEC problem, it would cause associated caution/warning lights to come on as well as registering on the FADEC memory. So with that in mind, there would be no doubt as to what happened.............

[Shawn Coyle]

They should be able to download data from the engine to show what happened. The FADEC records stuff every 1.2 seconds or so.
It should also record fault codes and the like and they are able to be seen by some clever switchology by the maintenance folks.
What were they doing when the alleged malfunction occurred?

[TukTuk BoomBoom]

A few years ago i watched a couple of EMS pilots on the 407 cockpit procedures trainer at Bell shoot approaches and deal with gov. failures.
80% were huge accident with big rates of descent.
Looked like quite a handful...

[jayteeto]

The military Chinook thread has gone on for years and talks about FADEC malfunctions. In the early days they were getting unexplained shutdowns and runaways. This was rumoured to be early software glitches, now supposedly fixed. Could a similar problem bypass any warning or recording systems and fool the engineers??

[SHortshaft]

407/McG/Shawn

I don’t know what the indications were that the crew was faced with other than rotor rpm decay, or what the FADEC read out said. I was relaying information I found in the press and I heard in the ‘bar’ (probably equally inaccurate sources).

I guess with the information retained in the FADEC there will at least be some substantiation of the pilot’s report, and hopefully some follow up in the safety reviews in due course.

It would seem from the lack of reports in the response that this event was ‘unusual’.

[NickLappos]

The data from a FADEC is vast, the typical one records all significant parameters at high rate (I am not sure, Shawn, where you get the 1.2 second rate, most FADECs crunch at 80 Hz and simply record that data stream).

I am surprised that the operator claims a cause, in the absence of official investigation announcements, and frankly have difficulty them.

[Shawn Coyle]

Nick:
the 1.2 seconds came from an accident I'm working on that only had data at that interval (Bell 407).
Even at that I was able to get some good data- but not nearly as much as I'd hoped for.
Some incidents that happened to a brand I used to work for showed that the DEC in those helicopters didn't store anything worthwhile for accident / incident purposes. In one case the company was saved by the EGPWS (enhanced Ground Prox Warning System) storing everything like engine torques, etc.
Of course, I'm sure that under your expert advice and guidance (and I'm being serious) the Sikorsky machines all had good data storage for engine as well as airframe stuff (I've already heard about how useful it's turned out to be in at least one accident).
Wish everyone was in the same boat.

[tottigol]

A degraded FADEC would (should) at least alert the pilot to the situation with a LOUD screeching horn that can only be sillenced by reverting to manual control (as in a 212/412) of the fuel metering.
The Chandler Evans system that Bell adopted for their 407/430 types is a single channel type with manual back-up as opposed to other more modern European types (Shawn can confirm this).
Before Bell rectified the problem some years back (in the 407, they never changed it in the 430:D ), the FADEC system could fail to either fixed fuel flow or manual and if on a "hot" approach to land, it could take several seconds to regain power, resulting in those "splattering" landings witnessed in the CPT.

[Matthew Parsons]

There's this one http://www.ntsb.gov/Recs/letters/2004/A04_68_69.pdf However, it was not kept quiet. Are you only interested in the quiet ones or any Bell 407 FADEC failures?

Did the operator say why they thought it was a FADEC problem? Perhaps they did have the lights and tone.

Like all crashes, the discussion is interesting, but wait for the investigation before making conclusions.

[SHortshaft]

The link provides interesting reading. Thank you MP for that.

Can anyone advise whether the NTSB’s recommendations were ever implemented, or if RR has come up with a fix?

To have to wait six seconds would, I am sure, seem like an eternity when all the lights and warning horns have just gone off, especially if you are at low level.

It would seem from the report that there have been enough FADEC incidents to make the average pilot a little nervous when operating at lower altitudes.

[Shawn Coyle]

The Bell 407 was the first single engine, single channel FADEC. There were bound to be mistakes when you step away from previous ways of doing things. It was a bold move, and for the most part it worked.
All you have to do is look at the NTSB's accident records for the Bell 206 series for the past 5 years and see the number of unexplained engine failures (not counting fuel exhaustion or bad fuel) to see how the FADEC on the 407 is really not that bad.
I'll leave the interested pprune'r to look things up.
(and compare the FAA reaction to those engine failures to their reaction to the third - count 'em -3- engine failures on the Boeing 757 in the past 5 years....)